The Omicron variant appears to produce less severe disease than the globally dominant Delta strain, but should not be categorised as “mild”, the WHO has declared.

The agency said early studies showed that when compared with Delta there was a reduced risk of hospitalisation from the variant which first emerged in November.

And there appears also to be a reduced risk of severe COVID-19 for younger and older people, although the WHO said the impact on the elderly remains unclear as most of the cases studied have been in younger people.

“While Omicron does appear to be less severe compared to Delta, especially in those vaccinated, it does not mean it should be categorised as mild,” its director general Tedros Adhanom Ghebreyesus told reporters last week.